This invention relates to dental pins, and more particularly to an elongated dental pin having a plurality of contiguous coaxial pin sections with each section sequentially moved into a projecting position from a magazine holder. The projecting pin shears off upon insertion into an aperture in the tooth stub and the next successive pin is projected.
In the formation of a dental superstructure onto a tooth stub, it is typical to insert one or more dental pins into the tooth stub with portions of the pins projecting upwardly from the surface of the tooth stub. The superstructure is then built up onto the tooth stub with the projecting portions of the pins used to aid in the retention of the superstructure onto the tooth stub. A number of such dental pins are often placed adjacent each other in order to aid in the retention of the superstructure.
An improved arrangement has been described in U.S. Pat. No. 3,675,328 assigned to the assignee of the present invention which describes an elongated dental pin having a plurality of individual threaded sections with each threaded section being separated from an adjacent section by a reduced diameter throat section. Each of the successive throat section are of increased diameter with respect to a proceeding throat section. The pin includes a single enlarged head. The head of the multiple sectioned dental pin is placed in a shank and the most remote threaded section is inserted into an aperture in a tooth stub. Upon reaching complete insertion, that remote section will shear from the remainder of the dental pin at its adjacent throat section. The next successive threaded section is then available for insertion in another aperture in the tooth stub. This next section will likewise shear at its adjacent throat section. Since the throat sections sequentially increase in size, the lowermost threaded section which is being inserted will shear before next two sections. The above described system is available from Whaldent International under the trademark TMS or Thread Made System.
An improvement in the multiple sectioned pin is described in U.S. Pat. No. 4,202,101. This patent relates to what is presently available from Whaldedent International under the trademark Link Series. In this structure, there is likewise provided multiple threaded sections with each section being separated from the next adjacent section by a reduced diameter throat portion. The respective diameters of the throats are successively increased in size to be sure that the lower most threaded section shears before the next adjacent subsequent section.
In the Link Series pin, the upper end which is inserted in the shank, includes a flattened tang with an arcuate outer edge to permit swaying of the pin within its receiving chamber. The sway facilitates insertion of the pin into the aperture and aids in the positioning of the pins.
In each of the above described systems, the pin itself comprises uniform threaded sections with the only discontinuity being the reduced diameter throat portions. Only a part of each of the threaded sections is inserted into the tooth stub while an upper part of each threaded section remains above the tooth stub for retention of the superstructure. Such upper parts can be bent or the entire pin can be angularly inserted in a tooth stub in order to provide an annular positioning of the upper projecting part to aid in the retention of the superstructure.
With the prior art pins, the entire pin with all its multiple sections projects from the shank and is retained within the shank by a single enlarged head portion at one end of the pin. Because all of the sections are always projecting from the shank, it is necessary to have the successive throats of increased diameter size to be sure that the lower most section will sever before the subsequent sections.